# HG changeset patch
# User kmo
# Date 1361876726 0
# Node ID 265a0d86c9ffa47a61f79e3f47373599d68203a3
# Parent  b57c48f161797a72a681e119021a40c1af5ee98e
7087570: java.lang.invoke.MemberName information wrong for method handles created with findConstructor
Summary: REF_invokeSpecial DMHs (which are unusual) get marked explicitly; tweak the MHI to use this bit
Reviewed-by: jrose, twisti

diff -r b57c48f16179 -r 265a0d86c9ff jdk/src/share/classes/java/lang/invoke/DirectMethodHandle.java
--- a/jdk/src/share/classes/java/lang/invoke/DirectMethodHandle.java	Thu Feb 21 20:01:22 2013 +0000
+++ b/jdk/src/share/classes/java/lang/invoke/DirectMethodHandle.java	Tue Feb 26 11:05:26 2013 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -55,8 +55,7 @@
     }
 
     // Factory methods:
-
-    static DirectMethodHandle make(Class<?> receiver, MemberName member) {
+    static DirectMethodHandle make(byte refKind, Class<?> receiver, MemberName member) {
         MethodType mtype = member.getMethodOrFieldType();
         if (!member.isStatic()) {
             if (!member.getDeclaringClass().isAssignableFrom(receiver) || member.isConstructor())
@@ -64,8 +63,14 @@
             mtype = mtype.insertParameterTypes(0, receiver);
         }
         if (!member.isField()) {
-            LambdaForm lform = preparedLambdaForm(member);
-            return new DirectMethodHandle(mtype, lform, member);
+            if (refKind == REF_invokeSpecial) {
+                member = member.asSpecial();
+                LambdaForm lform = preparedLambdaForm(member);
+                return new Special(mtype, lform, member);
+            } else {
+                LambdaForm lform = preparedLambdaForm(member);
+                return new DirectMethodHandle(mtype, lform, member);
+            }
         } else {
             LambdaForm lform = preparedFieldLambdaForm(member);
             if (member.isStatic()) {
@@ -79,6 +84,12 @@
             }
         }
     }
+    static DirectMethodHandle make(Class<?> receiver, MemberName member) {
+        byte refKind = member.getReferenceKind();
+        if (refKind == REF_invokeSpecial)
+            refKind =  REF_invokeVirtual;
+        return make(refKind, receiver, member);
+    }
     static DirectMethodHandle make(MemberName member) {
         if (member.isConstructor())
             return makeAllocator(member);
@@ -114,6 +125,10 @@
 
     //// Implementation methods.
     @Override
+    MethodHandle viewAsType(MethodType newType) {
+        return new DirectMethodHandle(newType, form, member);
+    }
+    @Override
     @ForceInline
     MemberName internalMemberName() {
         return member;
@@ -357,6 +372,21 @@
         ((DirectMethodHandle)mh).ensureInitialized();
     }
 
+    /** This subclass represents invokespecial instructions. */
+    static class Special extends DirectMethodHandle {
+        private Special(MethodType mtype, LambdaForm form, MemberName member) {
+            super(mtype, form, member);
+        }
+        @Override
+        boolean isInvokeSpecial() {
+            return true;
+        }
+        @Override
+        MethodHandle viewAsType(MethodType newType) {
+            return new Special(newType, form, member);
+        }
+    }
+
     /** This subclass handles constructor references. */
     static class Constructor extends DirectMethodHandle {
         final MemberName initMethod;
@@ -369,6 +399,10 @@
             this.instanceClass = instanceClass;
             assert(initMethod.isResolved());
         }
+        @Override
+        MethodHandle viewAsType(MethodType newType) {
+            return new Constructor(newType, form, member, initMethod, instanceClass);
+        }
     }
 
     /*non-public*/ static Object constructorMethod(Object mh) {
@@ -395,6 +429,10 @@
         @Override Object checkCast(Object obj) {
             return fieldType.cast(obj);
         }
+        @Override
+        MethodHandle viewAsType(MethodType newType) {
+            return new Accessor(newType, form, member, fieldOffset);
+        }
     }
 
     @ForceInline
@@ -434,6 +472,10 @@
         @Override Object checkCast(Object obj) {
             return fieldType.cast(obj);
         }
+        @Override
+        MethodHandle viewAsType(MethodType newType) {
+            return new StaticAccessor(newType, form, member, staticBase, staticOffset);
+        }
     }
 
     @ForceInline
diff -r b57c48f16179 -r 265a0d86c9ff jdk/src/share/classes/java/lang/invoke/MethodHandle.java
--- a/jdk/src/share/classes/java/lang/invoke/MethodHandle.java	Thu Feb 21 20:01:22 2013 +0000
+++ b/jdk/src/share/classes/java/lang/invoke/MethodHandle.java	Tue Feb 26 11:05:26 2013 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1250,8 +1250,6 @@
     /*non-public*/
     MethodHandle viewAsType(MethodType newType) {
         // No actual conversions, just a new view of the same method.
-        if (!type.isViewableAs(newType))
-            throw new InternalError();
         return MethodHandleImpl.makePairwiseConvert(this, newType, 0);
     }
 
@@ -1268,6 +1266,11 @@
     }
 
     /*non-public*/
+    boolean isInvokeSpecial() {
+        return false;  // DMH.Special returns true
+    }
+
+    /*non-public*/
     Object internalValues() {
         return null;
     }
diff -r b57c48f16179 -r 265a0d86c9ff jdk/src/share/classes/java/lang/invoke/MethodHandleImpl.java
--- a/jdk/src/share/classes/java/lang/invoke/MethodHandleImpl.java	Thu Feb 21 20:01:22 2013 +0000
+++ b/jdk/src/share/classes/java/lang/invoke/MethodHandleImpl.java	Tue Feb 26 11:05:26 2013 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -367,11 +367,11 @@
 
         @Override
         MethodHandle viewAsType(MethodType newType) {
-            MethodHandle mh = super.viewAsType(newType);
+            if (newType.lastParameterType() != type().lastParameterType())
+                throw new InternalError();
+            MethodHandle newTarget = asFixedArity().viewAsType(newType);
             // put back the varargs bit:
-            MethodType type = mh.type();
-            int arity = type.parameterCount();
-            return mh.asVarargsCollector(type.parameterType(arity-1));
+            return new AsVarargsCollector(newTarget, newType, arrayType);
         }
 
         @Override
@@ -379,6 +379,12 @@
             return asFixedArity().internalMemberName();
         }
 
+        /*non-public*/
+        @Override
+        boolean isInvokeSpecial() {
+            return asFixedArity().isInvokeSpecial();
+        }
+
 
         @Override
         MethodHandle bindArgument(int pos, char basicType, Object value) {
diff -r b57c48f16179 -r 265a0d86c9ff jdk/src/share/classes/java/lang/invoke/MethodHandleInfo.java
--- a/jdk/src/share/classes/java/lang/invoke/MethodHandleInfo.java	Thu Feb 21 20:01:22 2013 +0000
+++ b/jdk/src/share/classes/java/lang/invoke/MethodHandleInfo.java	Tue Feb 26 11:05:26 2013 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -32,7 +32,6 @@
  */
 final class MethodHandleInfo {
    public static final int
-       REF_NONE                    = Constants.REF_NONE,
        REF_getField                = Constants.REF_getField,
        REF_getStatic               = Constants.REF_getStatic,
        REF_putField                = Constants.REF_putField,
@@ -48,12 +47,17 @@
    private final MethodType methodType;
    private final int referenceKind;
 
-   public MethodHandleInfo(MethodHandle mh) throws ReflectiveOperationException {
+   public MethodHandleInfo(MethodHandle mh) {
        MemberName mn = mh.internalMemberName();
+       if (mn == null)  throw new IllegalArgumentException("not a direct method handle");
        this.declaringClass = mn.getDeclaringClass();
        this.name = mn.getName();
-       this.methodType = mn.getMethodType();
-       this.referenceKind = mn.getReferenceKind();
+       this.methodType = mn.getMethodOrFieldType();
+       byte refKind = mn.getReferenceKind();
+       if (refKind == REF_invokeSpecial && !mh.isInvokeSpecial())
+           // Devirtualized method invocation is usually formally virtual.
+           refKind = REF_invokeVirtual;
+       this.referenceKind = refKind;
    }
 
    public Class<?> getDeclaringClass() {
@@ -78,7 +82,6 @@
 
    static String getReferenceKindString(int referenceKind) {
         switch (referenceKind) {
-            case REF_NONE: return "REF_NONE";
             case REF_getField: return "getfield";
             case REF_getStatic: return "getstatic";
             case REF_putField: return "putfield";
diff -r b57c48f16179 -r 265a0d86c9ff jdk/src/share/classes/java/lang/invoke/MethodHandles.java
--- a/jdk/src/share/classes/java/lang/invoke/MethodHandles.java	Thu Feb 21 20:01:22 2013 +0000
+++ b/jdk/src/share/classes/java/lang/invoke/MethodHandles.java	Tue Feb 26 11:05:26 2013 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1209,7 +1209,7 @@
             checkMethod(refKind, refc, method);
             if (method.isMethodHandleInvoke())
                 return fakeMethodHandleInvoke(method);
-            MethodHandle mh = DirectMethodHandle.make(refc, method);
+            MethodHandle mh = DirectMethodHandle.make(refKind, refc, method);
             mh = maybeBindCaller(method, mh);
             mh = mh.setVarargs(method);
             if (doRestrict)
diff -r b57c48f16179 -r 265a0d86c9ff jdk/test/java/lang/invoke/7087570/Test7087570.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/invoke/7087570/Test7087570.java	Tue Feb 26 11:05:26 2013 +0000
@@ -0,0 +1,326 @@
+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/* @test
+ * @bug 7087570
+ * @summary REF_invokeSpecial DMHs (which are unusual) get marked explicitly; tweak the MHI to use this bit
+ *
+ * @run main Test7087570
+ */
+
+import java.lang.invoke.*;
+import java.lang.reflect.*;
+import java.util.*;
+
+import static java.lang.invoke.MethodHandles.*;
+import static java.lang.invoke.MethodType.*;
+
+public class Test7087570 {
+    // XXX may remove the following constant declarations when MethodHandleInfo is made public
+    private static final int
+            REF_getField                = 1,
+            REF_getStatic               = 2,
+            REF_putField                = 3,
+            REF_putStatic               = 4,
+            REF_invokeVirtual           = 5,
+            REF_invokeStatic            = 6,
+            REF_invokeSpecial           = 7,
+            REF_newInvokeSpecial        = 8,
+            REF_invokeInterface         = 9,
+            REF_LIMIT                  = 10;
+
+    private static final TestMethodData[] TESTS = new TestMethodData[] {
+        // field accessors
+        data(DummyFieldHolder.class, "instanceField", getterMethodType(String.class), DummyFieldHolder.class, REF_getField),
+        data(DummyFieldHolder.class, "instanceField", setterMethodType(String.class), DummyFieldHolder.class, REF_putField),
+        data(DummyFieldHolder.class, "staticField", getterMethodType(Integer.class), DummyFieldHolder.class, REF_getStatic),
+        data(DummyFieldHolder.class, "staticField", setterMethodType(Integer.class), DummyFieldHolder.class, REF_putStatic),
+        data(DummyFieldHolder.class, "instanceByteField", getterMethodType(byte.class), DummyFieldHolder.class, REF_getField),
+        data(DummyFieldHolder.class, "instanceByteField", setterMethodType(byte.class), DummyFieldHolder.class, REF_putField),
+
+        // REF_invokeVirtual
+        data(Object.class, "hashCode", methodType(int.class), Object.class, REF_invokeVirtual),
+
+        // REF_invokeVirtual strength-reduced to REF_invokeSpecial,
+        // test if it normalizes back to REF_invokeVirtual in MethodHandleInfo as expected
+        data(String.class, "hashCode", methodType(int.class), String.class, REF_invokeVirtual),
+
+        // REF_invokeStatic
+        data(Collections.class, "sort", methodType(void.class, List.class), Collections.class, REF_invokeStatic),
+        data(Arrays.class, "asList", methodType(List.class, Object[].class), Arrays.class, REF_invokeStatic), // varargs case
+
+        // REF_invokeSpecial
+        data(Object.class, "hashCode", methodType(int.class), Object.class, REF_invokeSpecial),
+
+        // REF_newInvokeSpecial
+        data(String.class, "<init>", methodType(void.class, char[].class), String.class, REF_newInvokeSpecial),
+        data(DummyFieldHolder.class, "<init>", methodType(void.class, byte.class, Long[].class), DummyFieldHolder.class, REF_newInvokeSpecial), // varargs case
+
+        // REF_invokeInterface
+        data(List.class, "size", methodType(int.class), List.class, REF_invokeInterface)
+    };
+
+    public static void main(String... args) throws Throwable {
+        testWithLookup();
+        testWithUnreflect();
+    }
+
+    private static void doTest(MethodHandle mh, TestMethodData testMethod) {
+        Object mhi = newMethodHandleInfo(mh);
+
+        System.out.printf("%s.%s: %s, nominal refKind: %s, actual refKind: %s\n",
+                          testMethod.clazz.getName(), testMethod.name, testMethod.methodType,
+                          REF_KIND_NAMES[testMethod.referenceKind],
+                          REF_KIND_NAMES[getReferenceKind(mhi)]);
+        assertEquals(testMethod.name,           getName(mhi));
+        assertEquals(testMethod.methodType,     getMethodType(mhi));
+        assertEquals(testMethod.declaringClass, getDeclaringClass(mhi));
+        assertEquals(testMethod.referenceKind == REF_invokeSpecial, isInvokeSpecial(mh));
+        assertRefKindEquals(testMethod.referenceKind,  getReferenceKind(mhi));
+    }
+
+    private static void testWithLookup() throws Throwable {
+        for (TestMethodData testMethod : TESTS) {
+            MethodHandle mh = lookupFrom(testMethod);
+            doTest(mh, testMethod);
+        }
+    }
+
+    private static void testWithUnreflect() throws Throwable {
+        for (TestMethodData testMethod : TESTS) {
+            MethodHandle mh = unreflectFrom(testMethod);
+            doTest(mh, testMethod);
+        }
+    }
+
+    private static MethodType getterMethodType(Class<?> clazz) {
+        return methodType(clazz);
+    }
+
+    private static MethodType setterMethodType(Class<?> clazz) {
+        return methodType(void.class, clazz);
+    }
+
+    private static final String[] REF_KIND_NAMES = {
+        "MH::invokeBasic",
+        "REF_getField", "REF_getStatic", "REF_putField", "REF_putStatic",
+        "REF_invokeVirtual", "REF_invokeStatic", "REF_invokeSpecial",
+        "REF_newInvokeSpecial", "REF_invokeInterface"
+    };
+
+    private static final Lookup LOOKUP = lookup();
+
+    // XXX may remove the following reflective logic when MethodHandleInfo is made public
+    private static final MethodHandle MH_IS_INVOKESPECIAL;
+    private static final MethodHandle MHI_CONSTRUCTOR;
+    private static final MethodHandle MHI_GET_NAME;
+    private static final MethodHandle MHI_GET_METHOD_TYPE;
+    private static final MethodHandle MHI_GET_DECLARING_CLASS;
+    private static final MethodHandle MHI_GET_REFERENCE_KIND;
+
+    static {
+        try {
+            // This is white box testing.  Use reflection to grab private implementation bits.
+            String magicName = "IMPL_LOOKUP";
+            Field magicLookup = MethodHandles.Lookup.class.getDeclaredField(magicName);
+            // This unit test will fail if a security manager is installed.
+            magicLookup.setAccessible(true);
+            // Forbidden fruit...
+            Lookup directInvokeLookup = (Lookup) magicLookup.get(null);
+            Class<?> mhiClass = Class.forName("java.lang.invoke.MethodHandleInfo", false, MethodHandle.class.getClassLoader());
+            MH_IS_INVOKESPECIAL = directInvokeLookup
+                    .findVirtual(MethodHandle.class, "isInvokeSpecial", methodType(boolean.class));
+            MHI_CONSTRUCTOR = directInvokeLookup
+                    .findConstructor(mhiClass, methodType(void.class, MethodHandle.class));
+            MHI_GET_NAME = directInvokeLookup
+                    .findVirtual(mhiClass, "getName", methodType(String.class));
+            MHI_GET_METHOD_TYPE = directInvokeLookup
+                    .findVirtual(mhiClass, "getMethodType", methodType(MethodType.class));
+            MHI_GET_DECLARING_CLASS = directInvokeLookup
+                    .findVirtual(mhiClass, "getDeclaringClass", methodType(Class.class));
+            MHI_GET_REFERENCE_KIND = directInvokeLookup
+                    .findVirtual(mhiClass, "getReferenceKind", methodType(int.class));
+        } catch (ReflectiveOperationException ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static class TestMethodData {
+        final Class<?> clazz;
+        final String name;
+        final MethodType methodType;
+        final Class<?> declaringClass;
+        final int referenceKind; // the nominal refKind
+
+        public TestMethodData(Class<?> clazz, String name,
+                        MethodType methodType, Class<?> declaringClass,
+                        int referenceKind) {
+            this.clazz = clazz;
+            this.name = name;
+            this.methodType = methodType;
+            this.declaringClass = declaringClass;
+            this.referenceKind = referenceKind;
+        }
+    }
+
+    private static TestMethodData data(Class<?> clazz, String name,
+                                       MethodType methodType, Class<?> declaringClass,
+                                       int referenceKind) {
+        return new TestMethodData(clazz, name, methodType, declaringClass, referenceKind);
+    }
+
+    private static MethodHandle lookupFrom(TestMethodData testMethod)
+            throws NoSuchMethodException, NoSuchFieldException, IllegalAccessException {
+        switch (testMethod.referenceKind) {
+        case REF_getField:
+            return LOOKUP.findGetter(testMethod.clazz, testMethod.name, testMethod.methodType.returnType());
+        case REF_putField:
+            return LOOKUP.findSetter(testMethod.clazz, testMethod.name, testMethod.methodType.parameterType(0));
+        case REF_getStatic:
+            return LOOKUP.findStaticGetter(testMethod.clazz, testMethod.name, testMethod.methodType.returnType());
+        case REF_putStatic:
+            return LOOKUP.findStaticSetter(testMethod.clazz, testMethod.name, testMethod.methodType.parameterType(0));
+        case REF_invokeVirtual:
+        case REF_invokeInterface:
+            return LOOKUP.findVirtual(testMethod.clazz, testMethod.name, testMethod.methodType);
+        case REF_invokeStatic:
+            return LOOKUP.findStatic(testMethod.clazz, testMethod.name, testMethod.methodType);
+        case REF_invokeSpecial:
+            Class<?> thisClass = LOOKUP.lookupClass();
+            return LOOKUP.findSpecial(testMethod.clazz, testMethod.name, testMethod.methodType, thisClass);
+        case REF_newInvokeSpecial:
+            return LOOKUP.findConstructor(testMethod.clazz, testMethod.methodType);
+        default:
+            throw new Error("ERROR: unexpected referenceKind in test data");
+        }
+    }
+
+    private static MethodHandle unreflectFrom(TestMethodData testMethod)
+            throws NoSuchMethodException, NoSuchFieldException, IllegalAccessException {
+        switch (testMethod.referenceKind) {
+        case REF_getField:
+        case REF_getStatic: {
+                Field f = testMethod.clazz.getDeclaredField(testMethod.name);
+                return LOOKUP.unreflectGetter(f);
+            }
+        case REF_putField:
+        case REF_putStatic: {
+                Field f = testMethod.clazz.getDeclaredField(testMethod.name);
+                return LOOKUP.unreflectSetter(f);
+            }
+        case REF_invokeVirtual:
+        case REF_invokeStatic:
+        case REF_invokeInterface: {
+                Method m = testMethod.clazz.getDeclaredMethod(testMethod.name, testMethod.methodType.parameterArray());
+                return LOOKUP.unreflect(m);
+            }
+        case REF_invokeSpecial: {
+                Method m = testMethod.clazz.getDeclaredMethod(testMethod.name, testMethod.methodType.parameterArray());
+                Class<?> thisClass = LOOKUP.lookupClass();
+                return LOOKUP.unreflectSpecial(m, thisClass);
+            }
+        case REF_newInvokeSpecial: {
+                Constructor c = testMethod.clazz.getDeclaredConstructor(testMethod.methodType.parameterArray());
+                return LOOKUP.unreflectConstructor(c);
+            }
+        default:
+            throw new Error("ERROR: unexpected referenceKind in test data");
+        }
+    }
+
+    private static Object newMethodHandleInfo(MethodHandle mh) {
+        try {
+            return MHI_CONSTRUCTOR.invoke(mh);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static boolean isInvokeSpecial(MethodHandle mh) {
+        try {
+            return (boolean) MH_IS_INVOKESPECIAL.invokeExact(mh);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static String getName(Object mhi) {
+        try {
+            return (String) MHI_GET_NAME.invoke(mhi);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static MethodType getMethodType(Object mhi) {
+        try {
+            return (MethodType) MHI_GET_METHOD_TYPE.invoke(mhi);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static Class<?> getDeclaringClass(Object mhi) {
+        try {
+            return (Class<?>) MHI_GET_DECLARING_CLASS.invoke(mhi);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static int getReferenceKind(Object mhi) {
+        try {
+            return (int) MHI_GET_REFERENCE_KIND.invoke(mhi);
+        } catch (Throwable ex) {
+            throw new Error(ex);
+        }
+    }
+
+    private static void assertRefKindEquals(int expect, int observed) {
+        if (expect == observed) return;
+
+        String msg = "expected " + REF_KIND_NAMES[(int) expect] +
+                     " but observed " + REF_KIND_NAMES[(int) observed];
+        System.out.println("FAILED: " + msg);
+        throw new AssertionError(msg);
+    }
+
+    private static void assertEquals(Object expect, Object observed) {
+        if (java.util.Objects.equals(expect, observed)) return;
+
+        String msg = "expected " + expect + " but observed " + observed;
+        System.out.println("FAILED: " + msg);
+        throw new AssertionError(msg);
+    }
+}
+
+class DummyFieldHolder {
+    public static Integer staticField;
+    public String instanceField;
+    public byte instanceByteField;
+
+    public DummyFieldHolder(byte unused1, Long... unused2) {
+    }
+}
+